Electrochemical and spectroelectrochemical properties of manganese reconstituted myoglobin

Electrochemical and spectroelectrochemical properties of manganese(III) rec onstituted myoglobin (Mn(III)-Mb) have been investigated. No redox wave of Mn(III)-Mb was observed at a highly hydrophilic indium oxide electrode on w hich rapid direct electron transfer of native myoglobin took place, suggest ing the electron transfer reaction of Mn(III)-Mb at an indium oxide electro de is very slow. The rate constant of the chemical reduction of Mn(III)-Mb with dithionite was ca. 20 times smaller than that of native Mb. Using an o ptically transparent thin layer electrode (OTTLE) cell and Oxazine-170 perc hlorate, 5,9-bis(diethylamino)-10- methyl-benzo[a]phenoxazonium perchlorate , as an electron transfer mediator, the redox potential for the Mn(III)\Mn( II)-Mb couple was estimated to be -0.32 V versus Ag\AgCl (sat. KCl) at 25 d egrees C. (C) 1999 Elsevier Science S.A. All rights reserved.